Currently, DVD players are generally used for watching/listening to contents dedicated to playback. The DVD players make it possible not only to play back contents from their beginning position but also to perform an interactive operation with users such as a playback from a favorite position, a playback in a favorite order, a change of subtitles and a change of audio languages. However, general DVD players can play back only video contents, subtitle data and audio data that have already been recorded on the loaded disc.
The followings are proposed as improvement schemes for this. For example, the patent document 1 proposes a scheme in which an update audio file downloaded via a network is stored in a local storage built in a player and a file on a disc and a file in the local storage are virtually merged to configure a virtual file system, thereby allowing the player to play back an updated audio file.
Further, there is also the following proposal. For example, the patent document 2 proposes a scheme in which additional update contents downloaded via a network is stored in a local storage built in a player and a file on a disc and a file in the local storage are virtually merged to configure a virtual file system, thereby allowing the player to play back newly added contents.    Patent document 1: Japanese Patent Application Kokai Publication No. 2005-159589 (page 27, FIG. 4)    Patent document 2: Japanese Patent Application Kokai Publication No. 2006-33067 (page 41, FIG. 1)